during use. Filler plugs and caps and the bosses in which they are
installed must be carefully cleaned before removal and dispensing any
fluid.
Besides taking precautions while dispensing hydraulic fluids, you
must also ensure safe storage of fluids and observation of safety
regulations by the fluid handlers.
Fire Hazards.
Hydraulic fluids are quite flammable and must be
kept away from open flames, sparks, and objects heated to high
temperatures. Fluid leaks in aircraft are a definite fire hazard and
must be constantly looked for and promptly corrected.
The flash
point for MIL-H-5606 is 275 Fahrenheit.
Because MIL-H-83282 has a
flash point of 400 Fahrenheit, it is much safer to use and is
replacing MIL-H-5606.
Although the two fluids are compatible, care
must be taken so that a mixture of the two types has a volume of no
more than 3 percent MIL-H-5606. A mixture with a volume of more than
3 percent MIL-H-5606, degrades the flash point of MIL-H-83282.
The regulations for storing hydraulic fluids are the same as those
for other POL products, and their enforcement is equally as
important.
Toxicity.
Hydraulic fluids are not violently poisonous but are
toxic to an extent. Unnecessary breathing of the fumes and prolonged
contact of quantities of fluid with bare skin must be avoided.
SUMMARY
Hydraulics is the use of fluid under pressure to transmit force. In
Army aviation, hydraulics is used to operate retractable landing
gear, brakes, flight controls, propeller pitch, and loading ramps.
The
characteristics
of
hydraulic
systems
are
efficiency,
dependability, control sensitivity, flexibility of installation, low
space
requirements,
light
weight,
self-lubrication,
and
low
maintenance requirements.
Hydraulics operates on the principles of force and pressure.
The
unit of measurement of force is the pound, and the area of pressure
measurement is the square inch. Thus, force-pressure measurement is
expressed in pounds per square inch (psi).
Force is transmitted
through confined liquids without change in intensity to all parts of
the liquid.
17
AL0907
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